In many diverse industries, there are needs to feed sheets, strands or laminates from a supply to a utilization device or along a path from one utilization device to a succeeding utilization device. One common practice contemplates the use of rollers that are spring-urged and positively driven to engage and feed the sheets. In certain instances, a single spring-urged roller resting on a stack of sheets may be driven to peel the sheets one at a time from the supply stack. In other instances a pair of rollers are spring-urged together, and one roller is positively driven so that a sheet placed in the nip between the rollers is advanced between the rollers.
The use of spring-urged rollers may be eliminated by establishing a magnetic force acting to hold the rollers together while one roller is driven so that a sheet placed between the rollers is advanced therethrough. In British Pat. No. 2,017,655, issued to the Xerox Corporation, Rochester, N.Y. and published Oct. 10, 1979, there is disclosed a sheet-feeding device comprising a pair of vertically aligned rollers that are spring-urged apart by a spring. One of the rollers is electrically magnetized to draw the rollers together while the other roller is positively driven so that a sheet placed or advanced into the roller nip is frictionally driven between the rollers.
Permanent magnets have been used to hold vertically aligned rollers together while material is advanced between the rollers. An example of such an arrangement is shown in U.S. Pat. No. 3,256,570, issued June 21, 1966, to I. Kaino where two series of rollers in a textile drafting machine are magnetically held in abutting relation while textile strands are drawn between the rollers.
There is still a need to provide a roller-feed device which is the essence of simplicity, and is capable of eliminating the danger of nipping the fingers or clothing of an attending operator.